Completion of LCS implementation in JS issue#2252 (jainaman224#2313)

Longest_Common_Subsequence/Longest_Common_Subsequence.js

@@ -0,0 +1,47 @@
+/*
+Problem Statement - Given two sequences, find the length of longest subsequence present in 
+both of them.A subsequence is a sequence that can be derived from another sequence by 
+deleting some or no elements without changing the order of the remaining elements.
+*/
+
+const Longest_Common_Subsequence = (arr1, arr2) => {
+
+    let LCS_def = Array.from({ length: arr1.length + 1 },
+        () => Array.from({ length: arr2.length + 1 },
+            () => 0));
+
+    for (let i = 0; i < arr1.length + 1; i++){
+        for (let j = 0; j < arr2.length+1; j++){
+
+            if (i == 0 || j == 0) {
+                LCS_def[i][j] = 0;
+            }
+
+            // when the last character of both match, increase length of lcs by 1
+            else if (arr1[i - 1] == arr2[j - 1]) {
+                LCS_def[i][j] = LCS_def[i - 1][j - 1] + 1;
+            }
+
+            /* 
+            when the last character is not same, take maximum obtained by adding 
+            one character to one of the subsequences.
+            */
+            else {
+                LCS_def[i][j] = Math.max(LCS_def[i - 1][j], LCS_def[i][j - 1])
+            }
+        }
+    }
+
+    return `The length of longest subsequence is: ${LCS_def[arr1.length][arr2.length]}`;
+
+}
+
+
+// I/P and O/P Examples
+
+const inputSet1 = [10, 15, 20, 25, 30, 35, 40];
+const inputSet2 = [10, 12, 23, 25, 28, 30, 32, 40];
+const result = Longest_Common_Subsequence(inputSet1, inputSet2);
+
+// The length of longest subsequence is: 4
+console.log(result);